Fuse organization



R. w. E. MOORE 87,699

FUSE ORGANIZATION Filed June 4, 1955 i IMII% INVENTOR.

31 30 22 152465 WE/FM/fi WTM M ATTORNEYS Patented July 20, 1937 UNITED STATES PATENT OFFICE FUSE ORGANIZATION Application June 4,

6 Claim.

This invention relates to fuse organizations of the general type used to protect the individual circuits in residences and other buildings.

Lighting circuits in residences are customarily protected with the well-known plug fuses that are screwed into receptacles or sockets so connected that the current passing to the circuit must flow through the fuse. These fuses are accessible to all sorts of unskilled and ill-advised people; and it is now well-known that the circuits are frequently deprived of the necessary protection by the insertion of fuses of too high rating or by the insertion of tin foil, coins, etc., behind a blownout fuse. Accordingly, various fuse organizations have heretofore been devised for the purpose of preventing over-fusing and increasing the difficulty encountered by the uninitiated in attempting to complete the circuit by foreign objects inserted into the fuse g socket.

It is generally recognized that it is not commercially feasible to provide a fuse organization which would render it completely impossible for a skilled electrician to circumvent the fusing of the circuit. However, it is desirable so far as possible to make it very difficult for the uninitiated to circumvent the fusing; and particularly it is desirable to so construct the fuse organization that it cannot be thwarted with articles or materials which the uninitiated have readily at hand. The present invention is an improvement upon the prior art fuse organizations of the type discussed, and particularly it is an improvement upon the fuse organization disclosed in my prior Patent 1,990,953, issued February 12, 1935.

The general object of the invention is to provide a fuse organization of the general type disclosed in my prior patent which is even more 10 difficult for the uninitiated to circumvent.

A specific object of the invention is to so improve the fuse organization that when made with commercial manufacturing tolerances, it cannot be circumvented to a dangerous degree by the 45 insertion of finely stranded wire, which is one 1935, Serial No. 24,803

Fig. 5 is a top plan view of the receptacle shown in Fig. 3, drawn to smaller scale;

Fig. 6 is a bottom plan view of the exterior cap member of the fuse plug shown in Fig. 1, also on a reduced scale;

Fig. 7 is a detailed view in longitudinal section taken on the line 1-1 of Fig. 2;

Fig. 3 is a detail elevational view, looking from the line 88 in Fig. 1.

The fuse plug is built about an interior piece of molded insulating material designated as a whole by ID. This element I0 is molded in one piece and comprises an upper cylindrical wall II, a depending cylindrical skirt l2, and a partition member M from which there depends a perforated boss l3. Telescoped over the member It is a threaded sheet metal ferrule I5; and the upper part of the ferrule is provided with an inturned annular portion 15 (see Fig. 8) that lies against an annular ledge [6 on the exterior of member ID. The ferrule I5 is locked against rotation by lug lfia which projects upwardly from ledge l6 and extends through a cut away space in the inturned portion l5 of the ferrule. A disc I! of transparent material, such as glass or mica, is positioned on top of the upper cylindrical wall ll and an outer cap member it of molded insulating material is telescoped over the cylindrical wall H. The outer cap l8 may make a tight frictional fit with wall H, and additionally these parts may be cemented together. To aid the cement in adhering to the parts, the cemented surfaces may be roughened, as by fine ridges or grooves too small to illustrate.

A center contact button 2!] has a head which is co-extensive with the boss l3 and a shank which extends through the aperture in the boss l3. The shank initially terminates in a cup like portion similar to the end of a tubular rivet, but is stamped over to form a flange 22 which secures the button in place in the boss. Preferably, the face of the molded insulating material against which flange 22 is stamped, is formed with four radial channels 24 (Fig. 2) so that the metal of flange 22 extends down into these channels and fixes the head 20 against rotation relative to the boss H. A fuse link 25 extends from contact button 20, through opening 26, down channel 27 (formed on the interior of cap I8) to ferrule IS. The fuse link is suitably connected to head 20 as by solder at 28 and is also suitably connected to ferrule 15 as by solder at 29.

Venting for the fuse is provided in two ways. Adjacent to the shank of contact button 20, there (ill are four vertical grooves 3!! (Figs. 2 and '7) formed in the material of the partition M, and each of these vertical grooves 33 terminates in a horizontal groove 3! which extends radially adjacent the upper surface of the head of button 20. Thus gases generated by blowing of the fuse may escape via channels 38 and SI At the top of wall ll, there are four apertures 265 and gases may escape through these, pass upwardly through grooves 2'! to annular groove 33, and radially inward through grooves 34 to the free space immediately above the disc ll. Similarly, gases after passing through apertures may pass downwardly through grooves 2'5 and out to the air adjacent the upper edge of ferrule i5.

Referring to Figs. 3, l, and 5, the fuse receptacle is built up about a molded piece of insulated material 59, which has a depending boss 5!. The upper portion of the molded piece is providedfwith a cylindrical recess 52, and the depending boss is provided with a non-circular recess 53. A circuit breaker is formed by a metal plug biased upwardly by spring and provided with a head 55 which closely fits the recess 52. The lower end of plug 5Q extends into recess 53 and is there riveted to a washer fill which is so shaped as to be non-rotatively confined by the non-circular recess A sheet metal socket 58 has an inturned flange 59; and piece 59 is telescoped into the socket and against the flange. These parts may be held in assembled relation in any suitable way, as by fingers at which project into recesses these fingers being struck from the metal of the socket after piece 59 has been telescoped into the socket.

The socket construction shown in Fig. 3 may be incorporated in a cut-out base after the manner shown in my Patent 1,990,953, or it may be used as an adapter in a standard cut-out base after the manner shown in Schmidt Patent 1,863,383. In either case the fuse of Fig. 1 is screwed into the socket of Fig. 3 and part 59 acts as a fuse selector which rejects fuses of too high rating as explained in my Patent 1,990,953. With a fuse of permissible rating, metal contact button 29 engages head 56 to advance the circuit breaker and close the circuit.

As the fuse is being screwed in, button 20 rotates with the fuse and head 55 cannot rotate (due to washer 5?). The contacting surfaces of button 2i] and head 55 are cross hatched with fine grooves as shown in Figs. 1, 3, 5, and 7; and thus foreign material inserted in an attempt to bridge the circuit is caught in the grooves of the contacting faces and thereby shredded, broken, and torn. The interior of fuse skirt I2 is grooved with fine grooves. and the outer wall of socket piece 56 is correspondingly grooved at 55. The skirt i2 clears the part 59 by only the necessary manufacturing tolerance; and inserted foreign material is also caught and shredded and broken by grooves 64 and G5. The various grooves to catch foreign material are particularly effective against inserted pieces of stranded wire. It should also be noted that the head of contact button 26 is coextensive with boss i3 and enters recess 52 with only the necessary manufacturing tolerance, thereby still further safeguarding against bridging by foreign material.

While various prior art constructions can be made quite effective to forestall bridging if the parts be made to interfit accurately, it has been found that bridging can still be effected when variations in fit have been allowed sufficient to permit of production on a commercial scale at desirably low costs. With the present invention, however, dangerous bridging by inserted foreign material is exceedingly difficult, if not impossible, even when the device is made with the tolerances necessary for low cost commercial production.

I claim:

1. A fuse organization comprising: a socket for a plug fuse; a fuse selector mounted in the socket; a circuit breaker incorporated in the fuse selector, the circuit breaker having an exposed conducting face engageable by an inserted fuse to move the circuit breaker from open to closed position; and a plug fuse having an exposed conducting face to engage the exposed face of the circuit breaker and rotate relative thereto; the

cooperating faces of the fuse and circuit breaker being roughened to exert abrading action on foreign objects inserted into the socket in advance of the fuse.

2. A fuse organization comprising: a socket for a plug fuse, a fuse selector mounted in the socket, and a plug fuse for insertion into the socket, the selector and plug fuse having telescopically related surfaces of insulating material which are roughened to exert an abrading action on inserted foreign objects.

3. In a fuse organization of fuse socket and. plug fuse therefor, the socket having a fuse selector in telescopic relation with the fuse and also having a circuit breaker engaged and actuated by the fuse: the improvement which comprises roughened engaging faces on the fuse and circuit breaker and roughened telescopically related surfaces of insulating material on the fuse and selector, for the purpose of exerting an abrading action on foreign objects inserted into the socket in advance of the fuse.

4. A fuse organization comprising: a socket for a plug fuse; a fuse selector mounted in the socket, the fuse selector having cylindrical cavity and flat topped circuit breaker means reciprocably and non-rotatably mounted in said cavity, the top portion of the circuit breaker means making a close fit with the cavity; and a plug fuse having a contact button to engage and depress said circuit breaker means, the contact button also making a close fit with said cavity and the engaging surfaces of the contact button and circuit breaker means being roughened to exert a tearing action on foreign objects inserted in the socket in advance of the fuse.

5. A plug fuse having a projecting boss of insulating material and a metal contact button mounted on said boss and secured against rotation thereon, the button having an exposed roughened head to engage a circuit breaker in a suitable fuse socket.

6. A plug fuse having a projecting boss of insulating material and a metal contact button mounted on said boss and secured against rotation thereon, the button having an exposed roughened head to engage a circuit breaker in a suitable fuse socket and there being venting passages through the boss adjacent to the surface of said contact button.

RALPH W. E. MOORE. 

